This invention relates generally to machine filling of fluid materials into packages and particularly to a method of, and apparatus for, filling beverages or other fluid products to a predetermined weight into spouted bags in a manner well calculated to avoid microbial contamination and spoilage of the products.
A filling machine bearing particular pertinence to the present invention is described and claimed in Japanese Patent Publication No. 53-2395 (2395/1978) filed by the assignee of the instant application. Intended to fill spouted bags with a fluid food, this prior art machine comprises a collet assembly and a filling nozzle assembly mounted side by side on a swing arm in a germfree chamber. The swing arm is pivotable about a vertical axis for alternately moving the two assemblies to a position of registry with a bottom opening of the germfree chamber, besides being linearly movable up and down.
For filling a bag by this conventional machine the bag is placed on a weighing platform under the germfree chamber, with its capped spout caught by a fixed spout holder at the bottom opening of the chamber. The cap is first removed from the spout by the collet assembly. Then, with the filling nozzle assembly moved to the working position by the swing arm, the fluid is introduced into the bag to the prescribed weight as detected by the weighing machine including the platform. Thereafter the collet assembly is again moved to the working position to close the spout of the filled bag with the cap. Throughout the progress of this filling operation, filtered, heated air is continuously pumped into the chamber to maintain the same germfree.
Although well calculated to accomplish the purposes for which it is intended, this prior art filling machine has proved to have some drawbacks. First, since the spout of the bag is held in contact with the filling nozzle assembly while the fluid is being charged therein, it is difficult to accurately weigh the contained fluid. The precise weighing of the contained fluid is almost impossible in cases where the bag itself is housed in a carton or box.
Another drawback arises from the fact that the spout of the bag being filled is supported by the fixed spout holder. This member must lie as far inside the germfree chamber as possible in order to protect the open spout from contamination during the filling operation, making it difficult to manipulate the spout into and out of engagement with the spout holder.
The fixed spout holder gives rise to additional difficulties in making the chamber germfree prior to the commencement of successive cycles of the filling operation. The known filling machine sterilizes the chamber with high temperature steam introduced through the filling nozzle assembly. Owing to the presence of the fixed spout holder at its bottom opening, however, the chamber cannot be hermetically closed, so that it is difficult to raise the temperature of the steam under atmospheric pressure above 100.degree. C. Steam at temperatures not exceeding 100.degree. C. is unable to destroy some microorganisms that are highly resistant to heat. The complete sterilization of the chamber is made even more difficult because of the presence therein of the mechanisms for moving the collet assembly and the filling nozzle assembly to and away from the working position over the fixed spout holder.
A similar problem has been encountered with the steam sterilization of the inteior of the filling nozzle. As steam is passed through the filling nozzle under atmospheric pressure, as has been the case heretofore, its temperature does not rise beyond 100.degree. C. and so is insufficient to kill heat-resistant bacteria.
A further objection to the conventional filling machine also concerns its filling nozzle. Since this nozzle has a piston or valve member slidably mounted therein, metal particles created by abrasion, lubricant, and like contaminants may find their way into the food being dispensed therefrom. Still further, the nozzle assembly, which is of considerable axial dimension, has not been designed for ease of disassemblage and cleaning.